Syringe



Aug. 19, 1952 M, Q ABEL 2,607,342

SYRINGE Filed Nov. 24, 1950 Patented Aug. 19, 1952 oFFnCE y SYRINGEMartin s. Aberwainut creek, Calif.

Application November 24, 1950, Serial No. 197,239

8 Claims. l

My invention relates to syringes for handling measuring andadministering uids. While the basic .principles are widely applicable tofluidhandling devices of this broad classification, the invention isbeing initially embodied in a hypodermic syringe with outstandingadvantages and will be so described for the purposes of the presentdisclosure.

. With reference to the syringe as a finished article, an importantobject of my invention is to provide a precision hypodermic syringe thathas a long service life and has certain advantages in use with specialemphasis on free plunger action and easy cleaning.

A common cause of breakage in the use of medical syringes is thesticking of the usual glass plunger in the glass barrel caused bymaterials adhering to the plunger. In spite of careful cleaning, a glassplunger tends to accumulate a residual coating as it is exposed todifferent substances over a period of time, and such a coating makes theplunger stick both by increasing its diameter and by forming an adhesivebond between the plunger and barrel, especially when the plunger isinadvertently left in the barrel for even a short period of time.

I have discovered that this difficulty and cause of breakage can beeliminated by using a plunger having a surface provided by a uorinatedpolymer, more particularly a surface of polymerized tetrauoroethyleneresin. I have found that a surface of this particular resin gio-actingwith a glass surface has such an unexpectedly low coeicient of slidingfriction that it may aptly be called a self-lubricating plunger.

Such free plunger action requires, of course, a clean plunger surfaceand would be destroyed by any such residual coating as is commonly foundon glass plungers. Tetrafluoroethylene resin, however, resists theformation of any coating whatsoever since it has zero water absorptionand is, in effect, non-wettable. Most fluids commonly used inhypodermicsyringes are actually repelled by this synthetic resin andnothing sticks to it with any appreciable strength. Hence, there is nocleaning problem.

Tetrafluoroethylene resin is also peculiarly suitable for use as aplunger for handling a wide range of fluids because it is practicallyinert chemically and can withstand high temperatures. It is especiallysuitable for medical use for these reasons and because it can befabricated with precision and can be sterilized in the same manner asglass.

With reference to the method of making such (Cl. 12S-218) 2 devices, asimple inexpensive fabrication procedure is contemplated that issuitable for the economical mass production of precision hypodermicsyringes and the'like. In this regard, I have` in mind not onlyeliminating the usual grinding operations in the manufacture of suchmedical syringes but also manufacturing the parts with suiiicientlyclose dimensional tolerances as to make the barrels and plungers freelyinterchangeable. Such precision also makes it possible to use simplyapplied prefabricated volumetric scales on the barrels and thus avoidthe usual expensive methods of forming such scales directly on thebarrel surfaces.

Other objects and advantages of my invention will be apparent in thefollowing detailed description taken with the accompanying drawings.

In the drawings, which are to be regarded as merely illustrative, Y

Fig. 1 is a view partly in section and partly in elevation of a syringeconstructed in accord with. the invention; .Y

Fig. 2 is a sectional View of a modified form of plunger incorporating aglass reinforcement; and

Fig. 3 is a sectional view taken as indicated by the line 3 3 of Fig. 1.

The .syringe shown in Fig. 1 has a barrel l0 fabricated from asuitable'type of glass, for example a glass known by the trade namePyrex, and formed with the usual tip I I to receive hypodermic needles.The bore of the barrel is dimensioned with precision and is uniform indiameter throughout its length. The usual volumetric scale I4 may beetched on the glass of the barrel or formed thereon in any othersuitable manner, but a feature of the preferred practice of my inventionis theA use of a high temperature decalcomania or a silk screen stencilfor this purpose. .Such a scale is inexpensive and has the advantage ofproviding a smooth surface that is easily cleaned.

:The plunger l5 of the syringe has a surface of tetrafluoroethyleneresin which is a halogenated polymer such as vdisclosed in the PlunkettPat- 'uniformity throughout.

Il comprising a shell I8 of tetrafiuoroethylene resin encasing asuitable core or reinforcement 20 which may be made of any suitablesubstance. This particular reinforcement 2D shown in the drawing is madeof glass and is formed with a suitable head or flange 2l that isembedded in or gripped by the head or outer end portion 22 of the shellI8. The synthetic resin shell I8 protects the glass reinforcement 2l!Yagainst breakage and it willbe noted that while the outer en'd of theglass reinforcement is exposed' in 'thispar- Yticular embodiment of theinvention, the exposed l glass is set inward fromthe end of the resinshell for protection against shock.

suitable;lengths of so-called precision'borevglass,

Thisv tubing ismadeb'y a well known process of shrinking glasstubing oftheV desired` diameter.

tubing on an-'ac'curately ground` metalmandrel ofV uniform diameter forits entire length. The

precision bore tubing thereby producedhas an inner diameter of anextremely high degree of Such tubing is readily available commerciallyin a wide-variety of sizes.

In making my syringe barrelsthe required tipped ends are tooled or`shaped on the ends of lengths of precision'bore tubing in the mannernow commonly in use.

Since.v this procedure may bereli'ed on to produce' syringebarrelsr ofVpredetermined uniform internal diameter, I may use predeterminedVolumetricscales for the vrbarrels. The scale Hl' in Fig. 1. may, forexample, beprepared in advance in the formbf high temperaturedecalcomania transfer or silk screen stencil. and applied to the barrelafter fabrication has been completed. 'Ihe barrel'isthe'n putinto anoven for annealing tov relieve the strainsleft in the glass by thefabricationprocess; and atthe same timev the scale is:

thermally xed in character.

Since the described fabrication procedure makes it possible to controlthe* internal diameter of the barrel i1 as well as the diameter oftheplunger Vl5 within' close tolerances, even as close as approximatelyonetenthousandth ofv an inch,

the barrels and plungers may be manufactured in erlernen;v

together as a syringe so that the net loss by break-J age isonly onesyringe instead of two.

My specific disclosure of a preferred practice of the invention by wayof example will provide adequate guidance for other specific practicesof the invention and will suggest to those skilled in the art variouschanges and substitutions within the spirit and scope of my appendedclaims.

Having described my invention, I claim;

Y l. A syringe of the character described having in combination a glassbarrel and a plunger, the entire length of the plunger having acontinuous smooth surface of resinous fluorinated polymer.

quantityto itint'erchangeably. In sterilizing a l number of.suchsyrin'ges, it is notneces'sary to match thev barrels and plungers inindividual pairs after the sterilization' process, and when the barrelof one syringe and the plunger of another syringe are damaged ory brokenthe remaining lplungerand barrel may be assembled 2. A syringe of thecharacter described having in combination a glass barrel and a plunger,the

entire length ofthe plunger having a continuous smooth'surface ofpolymerzed tetraiiuoroethylene resin.

.3'. A syringe of the character described having in combination a glassbarrel and a one-piece plunger made: entirely of polymerizedtetrauoroetliyleneresin. f

4; A syringe of the character described having in. combination aglassbarrel, a plunger comprising polymerized tetrauoroethylene resin, and alreinforcement embeddedA in the plunger, the

resinl covering thei reinforcement throughout ther length of theplunger. f

5. A-'s'yringe as set forth in claim 4' inwhich said reinforcement is anelongated body ofglass.

6. A syringe of the character described having in combinationv a glassbarrel, a highA tempera'- ture decalcom'ania'on the surface of thevbarrel providing a volumetric scale and a plunger having a Workinglportion' at' least equal to the inside length of the 'barrel forrsliding' movement in thev barrel, said plunger having a continuoussurface of polymerized tetrafluor'oethylene resin through-V out thelength of its workingportion.

7. A syringe of the character describedL having. in'combinationa glassbarrel with a volumetric scale overlying the surfacethereof and aplunger. with a working portion at least equal in lengthy to the insidelength' of thebarrel, said working.. portion having a continuousrsurface of poly'-v merized tetrauoroethylene resin throughout' its:v

length. y

8. A syringe of the'character described having inA combination a glassbarrel, a plunger cmprisingpolymeriz'ed' tetrafiuoroethylene resin; anda glass rod embedded in the' resin with the' outer end of the glass rodexposed but spaced inwardV vfrom the outer end of the enveloping resin.

MARTIN S'. ABEL.

REFERENCES CITED The following references are of record in the file ofthisA patent:

FOREIGN PATENTS Number Country Date 3,520 Great Britain Mar. 5, 1890

